Reduction in light emitting diode (LED) package size is an important factor in the design of various portable display technologies requiring compact design such as cell phones or handheld computers. Traditionally, LED's are housed in packages that include multiple components which occupy an area much larger than the LED chip itself.
High brightness (HB) LED chips are being operated at ever-increasing power levels. Generally, the light conversion efficiency of LED chips is fairly low such that heat generated by the LED chip has to be removed by the package to the surroundings.
It is common that the combination of the LED substrate, the submount and the package material are poorly suited for transferring heat from the LED chip to the surroundings. Highly thermally conductive material such as metal mounts cannot be used alone because the electrical contacts to the LED must be electrically isolated. While those contacts can be isolated, the necessary materials usually create a decrease in the thermal conductivity that limits the physical size and power of the chips that can be used in the package.